Distance type product responsive relay



Aug. 19, 1947.

B. E. LENEHAN DISTANCE TYPE, PRODUCT RESPONSIVE RELAY.

Filed Feb. 16, 1945 c Q} P g, I '1? & l P

I Fag! WlTNESSES:

XXAW

Fly

Bernard EL 6/76/7fl/7.

ATTORN EY INVENTOR Patented Aug. 19, 1947 DISTANCE TYPE PRODUCTRESPONSIVE. RELAY Bernard E. Lenehan, Bloomfield, N. J assignor toWestinghouse Electric Corporation, East Pittsburgh, Pa., a corporationof Pennsylvania Application February 16, 1945, Serial No. 578,161

9 Claims.

My present invention relates to a new protective relay foralternating-current lines, the principal novel characteristic feature ofthe relay being that it has a distance-responsive characteristic, or amodified impedance characteristic which can be readily adjusted. Myinvention relates more particularly to a novelly energized wattmetric orproduct-responsive element which has readily adjustable characteristicsso that its impedance-circle can be separately adjusted as tocenter-placement and circle-radius.

An object of my invention is to energize the two windings of awattmetric relay with a current-compensated voltage, with suchadjustments as to be able to completely adjust the character'- isticcircle-response of the relay. The currentcompensated line-voltage isequal to the vectorial sum of an alternating-current function of alinederived voltage, plus the product of an alternating-current functionof a line-derived current times an impedance. Throughout thespecification, when I refer to a wattmetric element or relay, I mean anyproduct-responsive element which develops a torque equal to the productof its two energized quantities times a function of the angle betweenthem, whether that angleiunction is a sine or a cosine or anyintermediate function.

In the accompanying drawing, Figure 1 is a characteristicresponse-circle diagram which will be referred to in the explanation ofmy invention, and Figs. 2:, 3, 4 and 5 are diagrammatic views ofcircuits and apparatus illustrating my invention in four difierent formsof embodiment.

If a cosine-responsive product-type relay is energized with two complexquantities, which may be two diverse alternating magnetic fiuxes 1=E-df(1) and it will produce a torque which is the absolute value of thealgebraic sum of the products of the respective terms, or

At the balance-point of the relay, the torque T will be zero. DividingEquation 3 by I and put- I ting the equation equal to zero, theconditions for the balance-point of the relay will be found to be 0=ez--z'(ac'+5) +di) (5) This is the equation of a circle, as will be seenfrom Fig. 1, where the circle 1 represents any circle, plotted onrectangular coordinates in terms of the line-resistance R and theline-reactance X, with the center C of the circle at the impedance56:20, and with a circle-radius C' P=Qo, where P is any point in thecircle. Then the locus of the line-impedance :2, or the locus of allvalues of the line-impedance which termihate in the circle, is the locusof the vector-sum ZU+QO=Z (6) Comparing Equations 5 and 8 and equatingequal powers of Z,

a a e. -cc; elem-1 1 and a diameter 2Qo equal to the difference (tb).

If we put where 0 is the angle by which the line-current i lags theline-voltage E, R is the line-resistance 3 up to the fault, and X is theinductive linereactance up to the fault, then This is the equation for acircle with a radius The slope of the circle-center impedance Z is a+RlThe displacement Z0 of the circle-center from the origin is A cosinerelay, responding to negative values of the torque T, and energized asset forth in Equations 1 to 25, will respond for all values of theline-impedance Z falling inside of the circle I, and will hold backagainst its back-stop for all values of the line-impedance Z fallingoutside of the circle.

If the angle of maximum response of the relay has any value 951- otherthan zero, so that response to the two energizing-quantities (p1 and Q52is a maximum when 1 lags $2 by an angle 1, then if the lagging angle of1 with respect to 2 is rather than 11 the relay-torque will be However,the Torque-Equations 3 and 20 are valid only for a cosine-relay, or arelay having a critical angle r 0. In order to make Equations 3 and 20valid for a relay having a critical angle (Pr, it will be necessary toreplace the energizing-quantity 1 of Equations 1 and 18 with anotherquantity 1o which leads 1 by the respouse-angle 1- of the relay, asshown by the equation For example, if the response-angle of the relay is(1:90, the relay will be a sine-responsive relay, responding to theproduct of its exciting quantities multiplied by the sine of thephaseangle between them, as shown by the torqueequation,

Equation 21 shows that we are interested only in the sum and difierenceof Ra and Rb, and in the sum and difference of Xu and Xb, and that thedifference-quantities (Ra-Rb) and (Xa--Xb) afiect only the circle-radiusQ0, and not the center-position (R0, X0). It will sometimes beconvenient, therefore, to make either (Ra-Rb) or (Xa-Xb) equal to zero.

Fig. 2 shows a form of embodiment of my invention in which Ra=Rb=R1 (30)Xa=X1+M4 (31) and Xb=X1-M4 (32) Then the circle-radius will be Qo=M4(33) the coordinates of the center will be at Ru==R1 (34) Xn=X1 (35) theslope of the center-line will be a & otan 1 R1 (36) and thecenter-displacement Will be ZO=VWXF=Z1 Still more generically, we knowthat we are interested only in the vector value of (cl-H3) and theabsolute value of [d-b], as shown in Equations 10 and 11. We may write,therefore, the general equations where Z3 and Z4 are any impedances.These reand a circle-radius Q0 expressed by the absolute value of Z4 asshown by the equation The absolute value of the impedance-component Zain Equation 40 expresses the ohms (or distance) displacement Z0 of thecircle-center C from the origin, while the phase-angle of theimpedance-component Z3 expresses the slope o of the circle-center lineZo.

Equation 41 shows that the phase-angle of the impedance-component Z4 isquite immaterial. This impedance-component Z4 may be pure'resistance,pure reactance, or any combination of the two.

There are man form in which these principles may be embodied.

Fig. 3 shows a form of embodiment of my invention in which thecenter-placement component Z3 is separated into two factors, a variablescalar quantity or absolute value Z3, and a variable phase-angle 3, andthe illustration is in tended to be symbolic of any means to that end.The angle-changing element is shown in the form of acompensator-impedance Z5 which is variable in phase-angle withoutchanging its magnitude; and the displacement-changing element is hown inthe form of a variable ratio or factor K, which affects the magnitude ofthe current Ki which is circulated through the compensator-impedance Zfrom the source of line-derived current I.

In Fig. 3, therefore,

The particular form of impedance Z5 in Fig. 3 is convenient for changingthe center-line angle o of the response-circle between an upper limit of90, or coincidence with the +X axis, corresponding to R5= oropen-circuited, or an upper limit of 85 if the maximum Value of R5 is(45.8)M, and a lower limit dependent upon the minimum practicable limitof R5 commensurate with an acceptable burden on the source oflinederived current I, or a lower limit of 50 if the minimum value of R5is (4.3)M, for example.

In Fig. 3, I have also illustrated the application of my invention to asine-type relay W having two force-reacting elements glue and oz, andproducing a force proportional to wz sin as discussed in connection withEquations 26 to 29. In order to make my invention applicable to such arelay, it is necessary to make the exciting-current in 1o lead theexciting-current in 2 by 90 when the same voltage is impressed on both9510 and m. This may be approximated by including a capacitor C inseries with the winding 1o and properly choosing the relative numbers ofturns in 1o and 52 to produce substantially the same flux in each, whenthe impressed voltage is the same.

In general, if the characteristic phase-angle of the relay is r so thatits maximum torque is produced when the angle between its twocooperating fluxes 1 and (#2 is r, then the relay-torque T is 12 cos(r), and it is necessary to cause the voltage-responsiveexcitation-components of the two fluxes to be dephased by (Pr, and tocause the corresponding current-responsive excitationcomponents of thetwo fluxes to be likewise dephased by r. In Fig. 3, a sine-responsiverelay W is presupposed, and hence the angle r is 90". In the otherfigures, a cosine-reponsive relay W is presupposed, and hence thecharacteristic relay-angle r is zero.

In Fig. 4, I have shown a further form of the phase-changing means, inthe form of an imped- 6 ance 2a which has different practical limits ofangle-variation.

Thus, in Fig. 4, if X6 is varied and Rs held constant, the circle-centerangle o may be changed, for example, from which is 240, corresponding toXs=(1.15)Rs, to 60, or 3-00, corresponding to Xe: (3.46) Re.

In all of the foregoing derivations, it has been assumed that therelay-current, 1'1-=f 1+1"2, or IT=I'1o+I'2, is negligibly small withrespect to the compensator-current I, within acceptable limits of error.

It will further be noted, from Equation 10, that the center-line angle#10 of the response-circle l of the relay is the same as the phase-angleof the average value, Zo:(d+b)/2, of the coefiicients a and b of theline-current response of the relay. Furthermore, the voltage-responsivecoefficient c in Equation 2 must be unity, as shown in Equation 9.Taking into consideration, also, the relations shown in Equations 41 and4'7 to 49, we may write the quantities to be multiplied, thus:

Then the circle-center displacement will be Zo=KZe (59) and thecircle-center angle will be L (60) and the circle-radius will be or theabsolute value of Z7, regardless of its phaseangle.

Since the phase-angle of Z7 is immaterial, the

impedance-component Z7 may be replaced by Z"1=Z a L 56 (62) yielding,from Equations 5'7 and 58,

1=E (KZ6+Z:8) 1:41pm; (63) 2=E- (KZ6Z8)IA6 (64) instead of e=sin wt. Inother words, the angle s in Equations 63 and 64 is in effect therelative angle between the current-responsive excitationcomponent andthe voltage-responsive excitation- It will be seen, therefore, that thecircle-center angle (pm is the difference between the phase-angle(4)6-(lm) of the current-responsive coefiicient, and the phase-angle('e) of the voltage-responsive coefiicient, at unity power-factor. Thus,instead of rotating the current-responsive terms through an angle s toobtain a center-line angle o=c, it would be possible to leave thephase-angle of the current-responsive term equal to zero, by putting/)G= /)e, and to obtain the desired center-line angle 0 c by rotatingthe response of the relay to the line-voltage El through a leading angle(e) while keeping the current-responsive terms in phase with theline-current i. Or both the current and voltage responses may berotated, yielding qbo: (6-(/)e) Many phase-shifting networks are known.

In Fig. 5, I have shown a voltage-shifting network 9 of a type which isdescribed and claimed in an application of H. J. Carlin, Serial No.583,926, filed March 21, 1945, and assigned to the Westinghouse ElectricCorporation. By a decrease of a secondary resistance R9 from infinity toa certain large value, with either position of the reversing-switch 3,the voltage E ma be shifted through any angle 9 up to 30, in eitherdirection, without materially changing its mag nitude, within acceptablelimits of error.

In Fig. 5, the circuit is such that It is believed that the variouscircuits and parts shown in Figs. 2 to 5 will be clear from theforegoing description. These figures may be briefly type windings 4n andm, and having a relaycontact I which closes when the relay responds. Thedetails of the relay circuit 8 which is controlled by the contact 1 arenot indicated, as my invention relates to the means for obtaining thecontact-closin response at 1, rather than the use which i made of thatresponse in the controlled relaying circuits 8.

In Fig. 2, a potential transformer |0 serves as a source of theline-voltage E, which is applied acros the terminals II and 12 of therelay. A line-current transformer |3 serves as a source of line-currentl, which is applied across the relay-terminals l4 and I5. The relayingcurrent l is circulated through a circuit including thecompensator-resistance R1, the compensator inductance X1, and theprimary winding of a mutual reactor 2M4, all of these values beingadjustable. The mutual reactor 2M4. is provided with a secondary winding23 having a mid-tap 2|.

In Fig. 2, the currentresponsive voltage-drop which appears across theresistor R1 and the reactor X1 is added to the line-derived voltage E,either directly, or through a suitable coupling transformer 24 havingany appropriate turnratio. The relay-terminal II i connected to one endof each of the relay-windings 1 and m. The other ends Olf the windings51 and 2 are connected to the terminals of the secondary winding 20 ofthe mutual impedance element 2M4. The mid-tap 2| of this secondarywinding 20 is connected to the other voltage-terminal |2 of the relaythrough the secondary winding of the compensator-transformer 24. Theresponse of the apparatus shown in Fig. 2 has already been discussed,and need not be further reviewed.

In Fig. 3, a sine-responsive wattmetric element W is utilized, asalready discussed, necessitating the inclusion of the capacitor C10 inseries with the relay-winding (m, as already explained. Thecurrent-responsive circuit, which is connected to the relay-terminals Mand IS in Fig. 3, includes the primary winding 25 of a variable-ratiotransformer K, as well as the primary winding of the previouslydescribed mutual reactor 2M4. The secondary winding of the transformer Kcirculates the current Kl through the impedance Z5, which consists of avariable resistance R5 in series with the primary winding of a fixedmutual reactance M. The resistance R5 is shunted by the primary windingof a fixed mutual reactance 2M. The two mutual reactors 2M and M havesecondary windings 21 and 2B which are serially connected, in oppositepolarities, between the voltage-terminal l2 and the mid-point 2|. Thecharacteristics of this circuit, as shown in Fig. 3, have already beendiscussed.

In Fig. 4, the same variable transformer K is utilized, but the mutualreactance 2M4 is re-- placed by a variable resistance 2R4, the voltageof which is applied to the relay-windings l and (in through atransformer 29 having a secondary winding 30 which is provided with amid-tap 3|. The mid-tap 3| is connected to the voltageterminal l2through two resistors R6 and His. The resistor R6 is shunted by thesecondary winding 32 of a transformer 33, which also has a primarywinding 34. The resistor 2R6 is shunted by a variable inductance Xs. Thesecondary winding 26 of the variable transformer K supplies the currentKi to the parallelcircuit combination 2R6 and X6, in series with thetransformer-winding 34, the latter being connected in reversed polarityso as to send the current Kl in the reversed direction through theresistor R6. These circuits of Fig. 4 have also been analyzed in thepreceding mathematical discussion, and need no further comment.

terminals II and I2 of the relay. The phasechanging network 9 consistsof a transformer 4|! having a primary winding 4| which is connected inseries circuit relation between the potential transformer H) and therelay-terminal H. The transformer 40 also has a secondary winding 42which is connected, through the reversing switch 3, between therelay-terminal l2 and the variable resistor R9. The other terminal ofthe variable resistor R9 is connected to the same potential-transformerterminal which is connected to the primary winding 4|;

The current-responsive circuit |4-|5in Fig, 5 contains the primarywinding 25 of the variable transformer K, and'the primary winding of themutual reactor 2M4, thesame as in Fig. 3.

The

secondary winding 26 of the variable transformer K circulates thecurrent Kl through the inductance X3 which is connected between thevoltageterminal l2 and the mid-tap 2|. The efiect of thecircuit-connection shown in Fig. 5 has already been discussed and needsno further explanation.

In all of the embodiments of my invention, it will be observed that Ihave provided means for independently-adjusting the radius Q0 and theposition of the center C of the response-circle I. The center-position Ccan be fixed either by separately adjusting its coordinates R0 and X0,or by separately adjusting its center-line slope 60 and its displacementZ0.

While I have illustrated and explained my invention in connection withfour different forms of embodiment, I wish it to be understood thatthere are many different forms of embodiment, as many variations may bemade, without departing from the essential features of my invention. Idesire, therefore, that the appended claims shall be accorded thebroadest construction consistent with their language and the prior art.

I claim as my invention:

1. An adjustable distance-type productresponsive relay having twodiverse cooperating alternating magnetic fluxes, means for so utilizinsaid fluxes as to produce a torque in response to the product of saidfluxes, multiplied by cos (T) where i the angle between said twocooperating fluxes and (Pr is the characteristic phase-angle of therelay, and two diverse fluxproducing mean for producing the respectivefluxes, characterized by each of said flux-producing means comprisingmeans for producing a voltage-responsive excitation-component inresponse to a line-derived voltage, and means for producing twocurrent-responsive excitationcomponents in response to a line-derivedcurrent, said two current-responsive excitation-components being added,one to the other, in one flux, and subtracted, one from the other, inthe other flux, a first adjustment-means for jointly varying a, firstone of the two current-responsive excitation-components of both fluxes,and a second adjustment-means for jointly varying the second one of thetwo current-responsive excitation-components of both fluxes, said twofluxproducing means including circuit-connection means for causing aphase-angle of substantially (,br to exist between each of thecorresponding excitation-components of the two cooperating fluxes.

2. An adjustable distance-type product-responsive relay having twodiverse cooperating alter nating magnetic fluxes, means for so utilizingsaid fluxes as to produce a torque in response to the produce of saidfluxes, multiplied by cos r) where o i the angle between said twocooperating fluxes, and r is the characteristic phase-angle of therelay, and two diverse fluxproducing means for producing the respectivefluxes, characterized by each of said flux-producing means comprising:means for producing a voltage-responsive excitation-component inresponse to a line-derived voltage, and means for producing twocurrent-responsive excitationcomponents which are out of phase with eachother in response to a line-derived current, and means for separatelyadjustin said currentresponsive excitation-components, said twofluxproducing means including circuit-connection means for causing aphase-angle of substantially 10 r to exist between each of thecorresponding excitation-components of the two cooperating fluxes.

3. The invention as defined in claim 1, characterized by said firstadjustment-means being a compensator-means comprising a variableresistance and a variable reactance traversed by a line-derived current.

4. The invention as defined in claim 1, characterized by said firstadjustment-means comprising means ior varying the magnitude, withoutsubstantially varying the phase-angle, of said first one of the twocurrent-responsive excitation-components of both fluxes, in combinationwith an adjustable phase-shifter means for varying the relativephase-angle between the voltageresponsive excitation-component and thefirst current-responsive excitation-component in each flux withoutsubstantially varyin their magnitudes.

5. An adjustable distance-type product-responsive relay having twodiverse cooperating alternating magnetic fluxes, mean for so utilizingsaid fluxes as to produce a torque in response to the product of saidfluxes, multiplied by cos (T), where is the angle between said twocooperating fluxes, and r is the characteristic phase-angle of therelay, and two diverse fluxproducing means for producing the respectivefluxes, characterized by each of said flux-producing means comprisingmeans for producing a voltage-responsive excitation-component inresponse to aline-derived Voltage, and means cfor producing acurrent-responsive excitation-component in response to a line-derivedcurrent, a first adjustment-means for causing substantially identicalquantities to be added to the two current-responsiveexcitation-components of the two fluxes whereby the sum of thetwocurrentresponses of the two fluxes is varied without substantiallychanging their difference, and a secondadjustment-means for causingsubstantially identical quantities to be added, in one case, andsubtracted, in the other case, from the respective current-responsiveexcitation-components of the two fluxes whereby the magnitude of thedifference of the two current-responses of the two fluxes is variedwithout substantially changing their sum, said two flux-producing meansincluding circuit-connection means for causing a phase-angle ofsubstantially r to exist between each of the correspondingexcitation-components of the two cooperating fluxes.

6. The invention as defined in claim 5, characterized by said firstadjustment-means being a compensator-means comprising a variableresistance and a variable reactance traversed by a line-derived current.

7. An adjustable distance-type product-responsive relay having twodiverse cooperating alternating magnetic fluxes, means for so utilizingsaid fluxes as to produce a torque in response to the product of saidfluxes, multiplied by cos (r), where the angle between said twocooperating fluxes, and r is the characteristic phase-angle of therelay, a first flux-producing means for producing a first one of saidcooperating fluxes in response to the vectorial sum of avoltage-responsive excitation-component in response to a line-derivedvoltage, plus a first current-responsive excitation-component inresponse to a line-derived current, plus a second currentresponsiveexcitation-component in response to a line-derived current, a secondflux-producing means for producing the second one of said cooperatingfluxes in response to the vectorial sum of the same voltage-responsiveexcitation-component, plus the same first current-responsiveexcitation-component, minus the second currentresponsiveexcitation-component, and separate adjustment-means for separatelyvarying the first and. second current-responsive excitationcomponents.

8. The invention as defined in claim 7, characterized by the means foradjusting said first current-responsive excitation-component being acompensator-means comprising a variable resistance and a variablereactance traversed by a line-derived current.

9. An adjustable distance-type product-responsive relay having twodiverse cooperating alterhating magnetic fluxes, means for so utilizingsaid fluxes as to produce a torque in response to the product of saidfluxes, multiplied by cos (-r), where is the angle between said twocooperating fluxes, and 1- is the characteristic phase-angle of therelay, a first flux-producing means for producing a first one of saidcooperating fluxesin response to the vectorial sum of avoltage-responsive excitation-component in response to a line-derivedvoltage, plus a first current-responsive excitation-component inresponse to a line-derived current, plus a second current-responsiveexcitation-component in response to a line-derived current, a, secondfluxproducing means for producing the second one of said cooperatingfluxes in response to the vectorial sum of the same voltage-responsiveexcitation-component, plus the same first currentresponsiveexcitation-component, minus the sec-- ond current-responsiveexcitation-component, a first adjustment-means for varyin the relativephase-angle between the voltage-responsive excitation-component and thefirst current-responsive excitation-component without substantiallyvarying their magnitudes, a second adjustmentmeans for varying themagnitude of the first current-responsive excitation-component withoutsubstantially varying its phase-angle, and a third adjustment-means forvarying the magnitude of the second current-responsiveexcitationcomponent.

BERNARD E. LENEI-IAN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,000,803 Van C. Warrington May7, 1935 2,115,597 Traver Apr. 26, 1938

